Obviously rejecting the 1,000,000 mpg , there are 7 data points.
The average is
30 + (-2 - 2 - 1 + 0 + 3 + 4 + 5)/7 = 30 + (-5 + 12)/7 = 31 mpg;
the median is 30 mpg, because there are equal numbers of values above and below it (3 each).
28, 28, 29, 30, 33, 34, 35 ... Add and divide by 7 ... 1,000,000 is ridiculous .. the outlier and leave it out